Thallium

formula: Tl; CAS Registry Number: 7440-28-0

Rare element which occurs naturally as trace element in many minerals

It is of limited commercial importance. Thallium is used e.g. in metal working industry, in the production of special-purpose glass and in measuring technology. Thallium sulfate is highly toxic and used as rodenticide and insecticide. It is banned, however, in many countries, e.g. Germany, Switzerland and the USA.

Thallium is released into the environment during weathering of rocks and anthropogenic activities. Water contaminations are mostly caused by industrial waste waters and atmospheric deposition. In aquatic ecosystems, thallium is bioavailable and quickly accumulated by organisms.
Through plants and animals thallium may enter the human food chain.

Environmentally relevant characteristics of thallium and its compounds include: